Telephone annunciator

ABSTRACT

A telephone annunciator is disclosed which includes a voice ROM with a prerecorded message which is played back in response to a call received from an unwanted caller. A line current modulator is coupled with the voice ROM and the telephone line. A DTMF tone decoder circuit is coupled with the telephone line for decoding at least one DTMF code signal for producing a trigger signal. An on/off control circuit is responsive to the trigger signal for turning on the voice ROM whereby the telephone line current is modulated by the modulator in accordance with the audio signal from the voice ROM. A start-up power supply includes a storage capacitor and stores a charge in response to a ring signal on the telephone line. A main power supply is connected with the telephone line to receive power therefrom when an off-hook signal is detected.

This application claims the benefit of U.S. Provisional Application No.60/023,067 filed Aug. 2, 1996.

FIELD OF THE INVENTION

This invention relates to annunciators and more particularly, it relatesto a telephone annunciator which may be activated by the telephone userto respond to an incoming call.

BACKGROUND OF THE INVENTION

There is a recognized need for providing a telephone user with somemeans for screening incoming telephone calls so that an unwanted callcan be responded to without the user participating in a telephoneconversation. The Walpole et al. U.S. Pat. No. 5,029,198 granted Jul. 2,1991 describes a telephone call responding system in which the telephoneuser, upon receiving an incoming telephone call, selects one of aplurality of call response messages by actuating a control key of theresponder system corresponding to the desired message. When activated,the responder system connects itself to the telephone line and deliversthe selected message. After delivering the message, the responder systemdisconnects itself from the telephone line until it is once againactivated by the user. Phillips U.S. Pat. No. 5,031,205 granted Jul. 9,1991 discloses an auto response telephone system that allows the user toautomatically screen calls and respond without even talking into thetelephone receiver. The system may be built into a conventionaltelephone or it may be in a separate case and operated as an accessory.The system stores several messages. The user picks up the telephone whencalled to identify the caller and then, the user can either speak to thecaller or automatically send one of the prerecorded messages.

A general object of this invention is to overcome certain disadvantagesof the prior art and to provide certain improvements in the circuitryand operation.

SUMMARY OF THE INVENTION

In accordance with this invention, an improved device is provided forenabling a telephone user to screen incoming telephone calls andselectively avoid the need for engaging in conversation with an unwantedcaller. This is accomplished by the telephone annunciator system whichcan be provided as a separate unit and easily installed by the telephoneuser to coact with the user's existing telephone set. The annunciator isof small size and is adapted for high volume production at relativelylow cost.

Further, in accordance with this invention, the annunciator is operablewith an existing telephone line by connection of it between thetelephone set and the line or by connecting it to any extension jack onthe telephone line. Operation of the annunciator by the user does notrequire physical access to the annunciator by the user after it isinstalled.

Further, in accordance with this invention, the annunciator is activatedby the user to play a recorded message by pressing a selected button onthe keypad of a conventional tone dial telephone set, such as theTouchtone™ telephone set. This is true in the case of a single telephoneset connected with the telephone line or any extension telephone setconnected with the telephone line. Preferably, this is accomplished bypressing the star (*) button on the telephone set.

Further, in accordance with this invention, if the annunciator isactivated by mistake, for example, the user may deactivate it and stopthe message by pressing the selected button again.

Further, in accordance with this invention, the annunciator is poweredfrom the telephone line and need not be provided with its own battery orother separate power source. This is accomplished by a start-up powersupply including a storage capacitor coupled with the telephone line forstoring a charge in response to a ring signal on the line. Additionally,the annunciator is provided with a main power supply which is connectedto the telephone line to receive power therefrom after the handset ofthe telephone is lifted from the cradle to operate the switch hooks.

Further, the start-up power supply includes a ring detector connectedacross the telephone line for producing a DC output voltage in responseto the ring signal on the telephone line.

Further, in accordance with this invention, the start-up power supplyincludes a full wave rectifier connected across the telephone linethrough a coupling capacitor.

Further, in accordance with this invention, a time constant controlcircuit is coupled with the storage capacitor and the coupling capacitorto bleed the coupling capacitor so that the time constant of the circuitis reduced to provide faster operation of the off-hook detector.

A complete understanding of this invention may be obtained from thedetailed description that follows taken with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the annunciator and its connection to a telephone set;

FIG. 2 is a block diagram showing the annunciator with a telephone set;

FIG. 3 is a block diagram of the annunciator system of this invention;and

FIG. 4 is a schematic diagram corresponding to the schematic diagram ofFIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, there is shown an illustrative embodimentof the invention in a telephone annunciator especially adapted forplaying a recorded message in response to an incoming telephone callunder the control of the telephone user. It will be appreciated as thedescription proceeds that this invention may be utilized in manydifferent applications and may be implemented in a variety of ways.

As shown in FIGS. 1 and 2, the annunciator 10 is connected to the wirepair of the telephone line 12 in parallel with the telephone set 14. Thetelephone line 12 is connected in a conventional manner to the telephonecompany central office The annunciator 10 is provided with a jack 16which is adapted to receive a connector 18 on the end of a connectorline of the telephone set. At the other end, the annunciator has aconnector line which terminates in a connector 22 adapted to be insertedinto a jack connected to the telephone line from the telephone company.The annunciator 10 obtains electrical power for its operation from thetelephone line. The telephone line is typically connected at thetelephone company exchange to a 48 volt DC source.

As shown in FIGS. 3 and 4, the tip (T) and ring (R) terminals of theannunciator are connected to the respective lines from the telephonecompany. Surge protection and reverse polarity protection are providedin a conventional manner by the protection circuit 26. In order toinitialize the annunciator 10, power is initially provided from a ringdetector 28, a voltage regulator 32 and an energy storage and filtercircuit 34. When the telephone set 14 is called, the ringing voltagefrom the telephone line is applied to the ring detector 28 through theprotection circuit 26. The ring detector is capacitively coupled bycapacitors 54 and 56 to the telephone line and includes a full waverectifier which develops a positive DC voltage which is applied to thevoltage regulator 32. The regulated voltage from regulator 32 is appliedacross a storage capacitor 36 which is connected in parallel with afilter capacitor 38. The storage capacitor 36 is charged by each of thesuccessive current bursts in the ring signal and holds a sufficientcharge for about five seconds after each burst to allow the annunciator10 to listen for an off-hook signal which will occur if and when theuser lifts the hand set from the cradle of telephone set 14.

The off-hook detector 42 is powered by the voltage on the storagecapacitor 36 during ringing and for about five seconds after the lastring. During this time it is listening for an off-hook signal. When thehandset is lifted from the cradle the telephone switch hooks are closedand the voltage on the telephone line drops significantly to a lowlevel, typically a value of around 10 volts. Thus, a circuit includingzener diode 44 causes the transistor 46 to turn off. Switching oftransistor 46 from on to off causes the main power supply 48 to turn onas will be described presently. In order to ensure reliable operation ofthe off-hook detector 42, the detector is provided with a time constantcontrol circuit including a transistor 52. Transistor 52 is turned on bythe voltage across storage capacitor 36 and is effective to bleed thecapacitors 54 and 56 in the ring detector so that the time constant ofthe circuit is reduced to provide faster and more reliable operation ofthe off-hook detector 42.

The main power supply 48 is controlled by a power supply switch 58which, in turn, is controlled by the off-hook detector 42. Whentransistor 46 in the off-hook detector 42 is turned off, the transistor62 is also turned off and this, in turn, causes the transistor 64 in themain power supply 48 to be turned on. Accordingly, current flows fromthe telephone line through the protection circuit 26 and transistor 64,resistor 66 to charge the storage capacitor 36. This provides for theannunciator 10 to be powered from the telephone line through the mainpower supply 48.

With the annunciator being powered by the main power supply 48, theannunciator is listening for either an on-hook signal which would turnoff the main power supply 48 or a “star code” signal which is producedon the telephone line by the activation of the “star” button on thetelephone set 14. The star code signal activates playback of aprerecorded response message to the party who initiated the telephonecall, as will be described below. If the user of the annunciator 10hangs up, the switchhook will be open and voltage will no longer besupplied from the telephone line to the annunciator which will thenbecome dormant unless the message is being played. In that case, theannunciator will hold the line in the off-hook condition to finish themessage and then hang up.

The DTMF (dual tone multiple frequency) decoder circuit 72 receives DTMFsignals from the telephone line and is capable of producing a codedoutput representing any one or all of the Touchtone™ buttons of thetelephone set 14. The DTMF decoder circuit 72 includes a DTMF decoder 74which is an integrated circuit identified as MT88L7OAS available fromMitel. A DTMF wake up circuit 76 applies a wake up signal to the decoder74 in response to the initializing voltage across the storage capacitor36 in the circuit 34. The DTMF decoder produces the decoded output onpins Q1, Q2, Q3 and Q4 corresponding to each DTMF signal on thetelephone line. The decoder outputs are applied to the star code signaldetector 78 which responds only to the star code.

The star code signal detector 78 produces a “talk trigger” signal whichis applied to the voice ROM on/off circuit 82. The talk trigger signal,is applied to the C input of the flip flop 84 causing the Q-not outputto go high since the data line is low. (Flip flop 84 is a dual D flipflop 4013 available from Motorola.) This causes the input of thetransistor 86 to go low which is applied as a switching signal to thevoice ROM turn on circuit 88. This turns on the transistor 92 in thevoice ROM turn on circuit 88. Transistor 92 supplies power from thepower supply 48 to the voice ROM power supply 94 which supplies power tothe voice ROM 96.

The voice ROM 96 is an integrated circuit MSS2105-701N available fromMosel. The voice ROM is custom programmed with a voice message which isto be played back from the ROM in analog form onto the telephone line.When the talk trigger signal is applied to the flip flop 84 it is alsoapplied to the voice ROM start circuit 98 which includes transistor 102.The talk trigger signal turns on the transistor 102 which activates thevoice ROM 96 to initiate the message playback. As long as the messageplayback continues, the “busy” pin on the voice ROM 96 is high andprovides a signal to turn transistor 86 on. This keeps the voice ROM 96turned on. When the playback of the message comes to an end, the busypin goes low and transistors 86 and 92 turn off which turns off voiceROM power supply 94 and the voice ROM 96 is deactivated.

The output of the voice ROM is an analog signal voltage which representsthe recorded voice signal. This output analog signal is applied to theinput of the line current modulator 97 which includes transistor 104.The analog signal is applied to the input of the transistor 104 which isconnected across transistor 92 in the voice ROM turn on circuit 88.Accordingly, the analog signal modulates the telephone line current andthus reproduces the prerecorded message at the receiver of the callingparty and at the receiver of the telephone set 14.

If user of the annunciator 10 desires for some reason to interrupt theplayback of the message from the voice ROM 94 before completion of themessage, the star button must be pressed a second time. This will causethe star code signal detector 78 to produce a second talk triggersignal. (The second talk trigger signal is interpreted as a “no talk”trigger signal.) When the second talk trigger signal is applied to theflip flop 84 it causes the Q-not output to go low which turns off thetransistor 86 in the voice ROM on/off circuit 82. This turns off thetransistor 92 in the voice ROM turn on circuit 88 and therebydisconnects the voice ROM power supply 94 from the main power supply 48.This deactivates the voice ROM 96 and the message is terminated.

The annunciator 10 is ready for operation once it is installed with thetelephone set as described above. In operation, the annunciator will bedormant until an incoming call rings the telephone set and causes theannunciator to be initialized so that it is in readiness to respond toan off-hook signal from the telephone set. The annunciator will beactivated to produce the stored message only when the star code signalis produced on the telephone line by the user pressing the star buttonon the telephone set. The annunciator then “speaks” the prerecordedmessage into the telephone line. After it has played back the completemessage, it will hang up the telephone set and return to its dormantstage. After the telephone user has pressed the star button, the usermay either remain on the line and “listen in” or hang up. If the userhangs up before the message is complete, the annunciator keeps the lineopen to finish the message. If the telephone user does not hang upbefore the message is completed, the line remains open until the userdoes hang up. If the user desires to interrupt the play back of therecorded message, the user must press the star button a second timewhich operates to stop the play back and the line remains open betweenthe user's telephone set and the calling party's telephone set.

In typical usage of the telephone set, the telephone user will desire toactivate the annunciator to play the recorded message only in case ofselected calls. In case the user receives an incoming call which isselected for use of the annunciator, the annunciator operates in thefollowing manner. When the call is received, the annunciator detects thering and it “listens” for an off-hook signal as long as the telephonecontinues to ring. If there is no off-hook signal, the annunciatorbecomes dormant and stops listening. If the user picks up the telephonethe annunciator detects the off-hook signal. It then “listens” for starcode signal and also listens for an on-hook signal. While the user has aconversation with the calling party, the annunciator continues to listenfor the star code signal or an on-hook signal. When the user hangs upthe telephone is disconnected from the line and the annunciator returnsto its dormant state in which it listens for a ring signal.

In case the user receives a telephone call which is not selected by theuser for use of the annunciator, the annunciator operation is asfollows. When the incoming call is received, the annunciator detects thering signal and listens for an off-hook signal. When the user picks upthe telephone the annunciator detects the off-hook signal and listensfor a star code signal or an on-hook signal. At any time after the usertakes the telephone set off-hook, during conversation or beforeconversation, the user may press the star button on the user's telephoneset and the annunciator plays the recorded message. (During the playback of the recorded message the annunciator listens for either a starcode signal or an on-hook signal.) If, after pressing the star button,the user hangs up, the annunciator will continue playing the recordedmessage until it is finished and then it will hang up.

The annunciator operates in the following manner in case of an incomingcall which is not answered. The annunciator detects the ring signal andis initialized for responding to subsequent control signals. Since thereis no off-hook signal within a predetermined time after the last ring,the annunciator goes dormant without activating play back of themessage.

Although the description of this invention has been given with referenceto a particular embodiment, it is not to be construed in a limitingsense. Many variations and modifications will now occur to those skilledin the art. For a definition of the invention reference is made to theappended claims.

What is claimed is:
 1. An annunicator for use with a telephone sethaving a keypad thereon and which is connected with a telephone line,said annunicator comprising: a pair of input terminals for connection ofthe annunicator with the telephone line, a voice ROM for storing amessage and for producing an audio signal corresponding to said messagewhen activated, said voice ROM having a pre-recorded voice messagestored thereon, a line current modulator having an input coupled withsaid voice ROM and an output adapted to be coupled with said telephoneline, an on/off control circuit for said voice ROM for selectivelyturning said voice ROM on and off, a decoder for producing a triggersignal, said decoder having an input adapted to be coupled with saidtelephone line and responsive to a predetermined DTMF code which isproduced on the telephone line when the telephone user presses apredetermined key of the telephone keypad, said on/off control circuitbeing coupled with said decoder and responsive to said trigger signalfor turning on said voice ROM whereby the telephone line current ismodulated by said line current modulator in accordance with the audiosignal from said voice ROM, a start-up power supply including a arectifier coupled with said input terminals by at least one DC blockingcapacitor and a storage capacitor connected with said rectifier forstoring a DC charge in response to a ring signal on the telephone line,a main power supply for supplying electrical power to the annunicatorafter said telephone set goes off-hook, and an off-hook detector circuitpowered by the start-up power supply and responsive to an off-hooksignal from said telephone set for connecting the main power supply tothe telephone line to receive power therefrom.
 2. The invention asdefined in claim 1 wherein: said start-up power supply includes a ringdetector connected across said input terminals for producing a DC outputvoltage in response to the ring signal on said telephone line.
 3. Theinvention as defined in claim 1 wherein: said start-up power supplyfurther includes a full wave rectifier connected across said inputterminals through a coupling capacitor, said rectifier being coupledwith said storage capacitor for charging said capacitor in response to aring signal on the telephone line.
 4. The invention as defined in claim3 including, a time constant control circuit coupled with the storagecapacitor and the coupling capacitor for bleeding the coupling capacitorin response to the charge on said storage capacitor.
 5. An annunicatorfor use with a telephone set having a keypad thereon and which isconnected with a telephone line, said annunicator comprising: a pair ofinput terminals for connection of the annunicator with the telephoneline, a voice ROM for storing a message and for producing an audiosignal corresponding to said message when activated, said voice ROMhaving a pre-recorded voice message stored thereon, a line currentmodulator having an input coupled with said voice ROM and an outputadapted to be coupled with said telephone line, an on/off controlcircuit for said voice ROM for selectively turning said voice ROM on andoff, a decoder for producing a trigger signal, said decoder having aninput adapted to be coupled with said telephone line and responsive to apredetermined DTMF code on the telephone line when the telephone userpresses a predetermined key of the telephone keypad, and said on/offcontrol circuit being coupled with said decoder and responsive to saidtrigger signal for turning on said voice ROM whereby the telephone linecurrent is modulated by said line current modulator in accordance withthe audio signal from said voice ROM.
 6. A method of operating anannunciator for a telephone, said annunciator comprising: a pair ofinput terminals connected with the telephone line, a voice ROM forstoring a message and for producing an audio signal corresponding tosaid message when activated, said voice ROM having a pre-recorded voicemessage stored thereon, a line current modulator having an input coupledwith said voice ROM and an output coupled with said telephone line, anon/off control circuit for said voice ROM for selectively turning saidvoice ROM on and off, and a decoder for producing a trigger signal andhaving an input coupled with said telephone line and responsive to apredetermined DTMF code which is produced on the telephone line when thetelephone user presses a predetermined key of the telephone keypad, saidon/off control circuit being coupled with said decoder and responsive tosaid trigger signal for activating said voice ROM and said modulationfor modulating the telephone line current in accordance with the audiosignal from said voice ROM, said method comprising the following stepswhich are performed by the user of the annunciator picking up thehandset of said telephone in response to ringing of the telephone,listening to the caller long enough to decide whether or not to proceedwith the call, if there is a decision against proceeding with the call,pressing said predetermined key on the telephone keypad to produce saidtrigger signal whereby the annunicator performs the following step:activating said voice ROM and said modulator to initiate playback ofsaid message to the caller.
 7. The method as defined in claim 6including the following steps performed by the user, hanging up thehandset after pressing said predetermined key on the telephone keypad.8. The invention as defined in claim 6 including the following stepsperformed by the user: staying on the line after pressing saidpredetermined key on the telephone keypad and listening for furtherinformation from the caller.